Design And Implementation Of Laser Range Finder Based On Phase Shift Measurement

Laser rangefinder is using laser which has high monochromatic and high coherence and good direction to achieve high precision measurement and detection.And laser rangefinder is one of the effective ways for distance measurement.It could also make distance measurement to the place where people can't reach more easier and safer[2].Now the laser rangefinder can be divided into the pulse laser rangefinder and the phase-shift laser rangefinder.The pulse rangefinder sends the laser signal to the target and reflect back.Then the laser rangefinder only records the round-trip time of the optical signal,and the distance to be measured can be obtained.The distance to be measured is equal to the speed of light multiply by a half of the round-trip time of the optical signal.Now the handheld and portable rangefinder widely used can reach several kilometers and the measurement accuracy can reach the meter level.The general satellite ranging use the pulse ranging to measure the distance and the measurement accuracy is about several centimeters.As we known the principle of the pulse ranging,the pulse rangefinder is good at the far ranging and the accuracy is low.The phase laser ranging sends the laser beam modulated to the target.Through the comparison of the laser beam launched and the laser beam received,the phase difference can be obtained.Through the phase difference,the distance to be measured can be obtained.Nowaday the measurement range of the phase-shift rangefinder can be several hundred meters and the measurement accuracy can reach several millimeters.So the phase-shift rangefinder is suitable for the medium and long distance and the measurement accuracy is good.With the development of modern science and technology,the measurement of phase difference could meet high accuracy.And the measurement range of this design is the medium and long distance.So the phase-shift rangefinder has priority for distance measurement.Through the analysis of existing laser ranging technologies as well as thecomparison of the performance of different technologies,phase-shift laser ranging method is proposed.On this basis,the basic principle of the phase-shift rangefinder and the related technology are introduced.At the same time,the realization of the software and hardware of the system is presented.The hardware design can be simplified as much as possible in the premise of realizing the function of each module of the phase ranging system and without affecting the accuracy of the phase-shift rangefinder,so as to reduce the cost of the hardware.In the phase ranging system,the signal source is generated by DDS(direct digital frequency synthesis)technique to produce The main vibration and the vibration signal.In data processing,with the use of double ADC sampling,discrete spectrum correction technology and fft,the results are more accurate.